Damian Lewis is in the thick of the action on Homeland, starring as the Marine Sergeant rescued after years in an Iraqi prison who is revealed to have been turned by the enemy.

But playing DCI Haskins in The Sweeney, who has the thankless task of trying to keep in Ray Winstone’s Jack Regan in check, he was strictly office bound while the rest of the cast were out playing cops and robbers.

“I wasn’t allowed out. I think Haskins was learning some Samba moves somewhere on his own,” he laughs. “Passing the time of day with a banana daiquiri on the corner.”

Despite his disappointment at missing out on the gunfights, he says the experience of being in the film was worth it.

“I just wanted to be in The Sweeney. I just thought it sounded like a right laugh – and it turned out to be! It was a treat. I got to spend a couple of weeks hanging out, working with Ray who I hadn’t worked with before.”

Instead of meeting in rehearsals, the two actors bonded with a day out at the races.

“We got off our t**s,” he says. “We were chucking money away. It was a very expensive day!”

At 41, Damian is a little too young to have watched the original series – where Haskins was played by Garfield Morgan – but was persuaded to take the role by director Nick Love.

“He sat me down and said ‘this is my vision for it’ and I said ‘that sounds fantastic’. It all happened so quickly.”

It also gave Damian, who is married to actress Helen McCory, a chance to return to his “homeland” to work, following his success in the States – and to compare working practices.

“The process of filming is pretty much the same.

“Catering is a bit better over there but only marginally. We did have quite a lot of sushi in on this. It wasn’t pie, mash and beer on The Sweeney, it was sushi and saki, which was very in keeping with the modern Sweeney.

“But otherwise, it’s very similar. The crew are all doing the same thing. British crews just have it over American crews in my view...and we work shorter hours in Britain.”

A one-time member of the RSC, Damian concentrated in stage work before his TV career took off. He worked a number of times at Birmingham Rep, playing Romeo in Romeo and Juliet, and as a killer who hosts a dinner party with his victim still hidden in the room in Rope.

Like fellow Etonian Dominic West, who was in HBO’s classic Baltimore-based The Wire, Damian has made a name for himself playing Americans.

On Band of Brothers, Damian was so convincing that even his fellow actors thought he genuinely was American.

He had the lead in the critically acclaimed series Life – again playing a former prisoner – this time he was an LA detective wrongly convicted of murder who was out to prove his innocence.

But it is the Golden Globe winning Homeland that has really established him in the US. President Obama is a fan and sat Damian and Helen on his table at a recent state dinner at the White House.

With all this media – and Presidential – attention, Damian said that they were all anxious that the second series, which is due to start soon on Channel 4, should live up to expectations.

“There is less anonymity compared to when we were filming the first time. I think the pressure comes from the writers down to deliver as highly as you did the first time and not to disappoint. We’re in a bit of a goldfish bowl this time.”